Health is the general condition of a person in all aspects. It is also sometimes defined as a level of functional and/or metabolic efficiency of an organism. The World Health Organization (WHO) defines health as “a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.” Every person is concerned with personal health, as one's personal health level enables or limits one's ability to perform actions in their life. People are not only concerned about the current state of their health, but they are also interested in actions they can take to improve their health, as well as behaviors that may have a negative impact on their health. Other parties, outside of an individual, may also have an interest in an individual's health level. For example, a health or life insurance company may factor a health level of an individual into pricing a premium for a policy because a person in poor health may be at a higher risk for debilitating disease or death.